D09–Efficient Absorption Enhancement Approaches for AlInAsSb Avalanche Photodiodes for 2-μm Applications

We describe two photon-trapping structures to enhance the quantum efficiency of AlInAsSb APDs for 2-μm detection. Finite-difference time-domain (FDTD) simulations show the absorption can be enhanced by more than 100 % with a triangular lattice photonic crystal, and nearly 400 % by applying a metal grating, for normal incidence at 2 µm.